struct ProfileSubmission {
    version: EntityVersion,
    full_name: String,
}

struct UserFormSubmission {
    version: EntityVersion,
    user_id: Option<String>,
    profile: ProfileSubmission,
    email_address: String,
}

#[server]
async fn submit(input: UserFormSubmission) -> Result<(), ServerFnError> {
   ...
}

view! {
        <ActionForm action=submit_form>
            <label>
                Full Name: <input type="text" name="input[profile[full_name]]" value=user_form_submission.profile.full_name required="required"/>
            </label>
            <label>
                Email Address: <input type="email" name="input[email_address]" value=user_form_submission.email_address required="required"/>
            </label>
            <input type="hidden" name="input[version]" value=user_form_submission.version />
            {
                if let Some(user_id) = user_form_submission.user_id {
                    view! {
                        <input type="hidden" name="input[user_id]" value=user_id />
                    }.into_any()
                } else {
                    view! {}.into_any()
                }
            }
            <input type="hidden" name="input[profile[version]]" value=user_form_submission.profile.version />
            <input type="submit" value="Submit" />
        </ActionForm>
    }